Methods of protecting aerospace components against corrosion and oxidation

ABSTRACT

Embodiments of the present disclosure generally relate to protective coatings on an aerospace component and methods for depositing the protective coatings. In one or more embodiments, a method for depositing a coating on an aerospace component includes depositing one or more layers on a surface of the aerospace component using an atomic layer deposition or chemical vapor deposition process, and performing a partial oxidation and annealing process to convert the one or more layers to a coalesced layer having a preferred phase crystalline assembly. During oxidation cycles, an aluminum depleted region is formed at the surface of the aerospace component, and an aluminum oxide region is formed between the aluminum depleted region and the coalesced layer. The coalesced layer forms a protective coating, which decreases the rate of aluminum depletion from the aerospace component and the rate of new aluminum oxide scale formation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. provisional patent applicationSer. No. 62/839,186, filed Apr. 26, 2019, which is herein incorporatedby reference.

BACKGROUND Field

Embodiments of the present disclosure generally relate to depositionprocesses, and in particular to vapor deposition processes fordepositing films on aerospace components.

Description of the Related Art

Turbine engines typically have components which corrode or degrade overtime due to being exposed to hot gases and/or reactive chemicals (e.g.,acids, bases, or salts). Such turbine components are often protected bya thermal and/or chemical barrier coating. The current coatings used onairfoils exposed to the hot gases of combustion in gas turbine enginesfor both environmental protection and as bond coats in thermal barriercoating (TBC) systems include both diffusion aluminides and variousmetal alloy coatings. These coatings are applied over substratematerials, typically nickel-based superalloys, to provide protectionagainst oxidation and corrosion attack. These coatings are formed on thesubstrate in a number of different ways. For example, a nickel aluminidelayer may be grown as an outer coat on a nickel base superalloy bysimply exposing the substrate to an aluminum rich environment atelevated temperatures. The aluminum diffuses into the substrate andcombines with the nickel to form an outer surface of the nickel-aluminumalloy.

A platinum modified nickel aluminide coating can be formed by firstelectroplating platinum to a predetermined thickness over thenickel-based substrate. Exposure of the platinum-plated substrate to analuminum-rich environment at elevated temperatures causes the growth ofan outer region of the nickel-aluminum alloy containing platinum insolid solution. In the presence of excess aluminum, theplatinum-aluminum has two phases that may precipitate in the NiAl matrixas the aluminum diffuses into and reacts with the nickel and platinum.

However, as the increased demands for engine performance elevate theengine operating temperatures and/or the engine life requirements,improvements in the performance of coatings when used as environmentalcoatings or as bond coatings are needed over and above the capabilitiesof these existing coatings. Because of these demands, a coating that canbe used for environmental protection or as a bond coat capable ofwithstanding higher operating temperatures or operating for a longerperiod of time before requiring removal for repair, or both, is desired.These known coating materials and deposition techniques have severalshortcomings. Most metal alloy coatings deposited by low pressure plasmaspray, plasma vapor deposition (PVD), electron beam PVD (EBPVD),cathodic arc, or similar sputtering techniques are line of sightcoatings, meaning that interiors of components are not able to becoated. Platinum electroplating of exteriors typically forms areasonably uniform coating, however, electroplating the interior of acomponent has proven to be challenging. The resulting electroplatingcoatings are often too thin to be protective or too thick that there areother adverse mechanical effects, such as high weight gain or fatiguelife debit. Similarly, aluminide coatings suffer from non-uniformity oninterior passages of components. Aluminide coatings are brittle, whichcan lead to reduced life when exposed to fatigue.

In addition, most of these coatings are on the order of greater than 10micrometers in thickness, which can cause component weight to increase,making design of the disks and other support structures morechallenging. It is desired by many to have coatings that (1) protectmetals from oxidation and corrosion, (2) are capable of high filmthickness and composition uniformity on arbitrary geometries, (3) havehigh adhesion to the metal, and/or (4) are sufficiently thin to notmaterially increase weight or reduce fatigue life outside of currentdesign practices for bare metal.

Therefore, improved protective coatings and methods for depositing theprotective coatings are needed.

SUMMARY

Embodiments of the present disclosure generally relate to protectivecoatings on an aerospace component and methods for depositing theprotective coatings. In one or more embodiments, a method for depositinga coating on an aerospace component includes depositing one or morelayers on a surface of the aerospace component using an atomic layerdeposition or chemical vapor deposition process, and performing apartial oxidation and annealing process to convert the one or morelayers to a coalesced layer having a preferred phase crystallineassembly. During oxidation cycles, an aluminum depleted region is formedat the surface of the aerospace component, and an aluminum oxide regionis formed between the aluminum depleted region and the coalesced layer.The coalesced layer forms a protective coating, which decreases the rateof aluminum depletion from the aerospace component and the rate of newaluminum oxide scale formation.

In one embodiment, a method for depositing a coating on an aerospacecomponent comprises exposing an aerospace component to a first precursorand a first reactant to form a first deposited layer on a surface of theaerospace component by a first atomic layer deposition process at atemperature between about 20 degrees Celsius to about 500 degreesCelsius, the aerospace component comprising nickel and aluminum. Thefirst deposited layer forms a protective coating on the aerospacecomponent. The protective coating protects the aerospace component fromcorrosion and oxidation and decreases a rate of depletion of aluminumfrom the aerospace component.

In another embodiment, a method for depositing a coating on an aerospacecomponent comprises depositing a first deposited layer on a surface ofan aerospace component by a chemical vapor deposition process, theaerospace component comprising nickel and aluminum, converting the firstdeposited layer to a crystalline phase, and forming an aluminum oxideregion between the first deposited layer and the aerospace component,the aluminum oxide region having a crystalline assembly. The firstdeposited layer and the aluminum oxide region form a protective coatingon the aerospace component. The protective coating protects theaerospace component from corrosion and oxidation and decreases a rate ofdepletion of aluminum from the aerospace component.

In yet another embodiment, a method for depositing a coating on anaerospace component comprises depositing a first deposited layer on asurface of an aerospace component by a chemical vapor deposition (CVD)process or an atomic layer deposition (ALD) process, the aerospacecomponent comprising nickel and aluminum, performing a first annealingand oxidizing process to convert the first deposited layer into apreferred crystalline phase, depositing a second deposited layer by theCVD process or the ALD process on the first deposited layer, andperforming a second annealing and oxidizing process to convert thesecond deposited layer into the preferred crystalline phase. The firstdeposited layer and the second deposited layer form a protective coatingon the aerospace component. The protective coating protects theaerospace component from corrosion and oxidation and decreases a rate ofdepletion of aluminum from the aerospace component.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlyexemplary embodiments and are therefore not to be considered limiting ofits scope, and may admit to other equally effective embodiments.

FIG. 1 is a flow chart of a method for depositing a coating on anaerospace component, according to one or more embodiments described anddiscussed herein.

FIGS. 2A and 2B are schematic views of protective coatings disposed on asurface of an aerospace component, according to one embodiment.

FIGS. 3A and 3B are schematic views of protective coatings disposed on asurface of an aerospace component, according to another embodiment.

FIGS. 4A and 4B are schematic views of protective coatings disposed on asurface of an aerospace component, according to yet another embodiment.

FIGS. 5A and 5B are schematic views of protective coatings disposed on asurface of an aerospace component, according to another embodiment.

FIGS. 6A and 6B are schematic views of protective coatings disposed on asurface of an aerospace component, according to yet another embodiment.

FIGS. 7A and 7B are schematic views of an aerospace component containingone or more protective coatings, according to one or more embodimentsdescribed and discussed herein.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

DETAILED DESCRIPTION

Embodiments of the present disclosure generally relate to protectivecoatings on an aerospace component and methods for depositing theprotective coatings. In one or more embodiments, a method for depositinga coating on an aerospace component includes depositing one or morelayers on a surface of the aerospace component using an atomic layerdeposition or chemical vapor deposition process, and performing apartial oxidation and annealing process to convert the one or morelayers to a coalesced layer having a preferred phase crystallineassembly. During oxidation cycles, an aluminum depleted region is formedat the surface of the aerospace component, and an aluminum oxide regionis formed between the aluminum depleted region and the coalesced layer.The coalesced layer forms a protective coating, which decreases the rateof aluminum depletion from the aerospace component and the rate of newaluminum oxide scale formation.

In one or more embodiments, a method for depositing a protective coatingon an aerospace component includes sequentially exposing the aerospacecomponent to a chromium precursor and a reactant to form achromium-containing layer on a surface the aerospace component by anatomic layer deposition (ALD) process. The chromium-containing layercontains metallic chromium, chromium oxide, chromium nitride, chromiumcarbide, chromium silicide, or any combination thereof.

In some embodiments, a nanolaminate film stack or protective coating isformed on the surface of the aerospace component, where the nanolaminatefilm stack or protective coating contains alternating layers of thechromium-containing layer and a second deposited layer. The aerospacecomponent can be sequentially exposed to a metal or silicon precursorand a second reactant to form the second deposited layer on the surfaceby ALD. The second deposited layer contains aluminum oxide, hafniumdoped aluminum oxide, aluminum nitride, silicon oxide, silicon nitride,silicon carbide, yttrium oxide, yttrium nitride, yttrium siliconnitride, hafnium oxide, hafnium nitride, hafnium silicide, hafniumsilicate, titanium oxide, titanium nitride, titanium silicide, titaniumsilicate, or any combination thereof. The nanolaminate film stack orprotective coating containing the alternating layers of thechromium-containing layer and the second deposited layer can be used asthe protective coating on the aerospace component. Alternatively, inother embodiments, the nanolaminate film stack or protective coatingdisposed on the aerospace component can be exposed to an annealingprocess to convert the nanolaminate film stack or protective coatinginto a coalesced film, which can be used as the protective coating onthe aerospace component.

FIG. 1 is a flow chart of a method 100 for depositing a coating on oneor more aerospace components, according to one or more embodimentsdescribed and discussed herein. FIGS. 2A-2B, FIGS. 3A-3B, FIGS. 4A-4B,FIGS. 5A-5B, and FIGS. 6A-6B are various schematic examples ofprotective coatings disposed on a surface of the aerospace component,according to one or more embodiments described and discussed herein. Theprotective coatings of FIGS. 2A-6B can be deposited or otherwise formedon the aerospace component by the method 100 described and discussedbelow. Moreover, while FIGS. 2A-6B illustrate various embodiments, theembodiments depicted in each of FIGS. 2A-6B may be combined with oneanother. For description purposes, FIGS. 2A-6B will be described priorto the method 100.

FIG. 2A illustrates a protective coating 200 deposited on an aerospacecomponent 202. The aerospace component 202 comprises a nickel alloycomprising aluminum. The protective coating 200 comprises a firstdeposited layer 204 comprising aluminum, such as aluminum oxide (Al₂O₃).The first deposited layer 204 may be deposited in an amorphous orcrystalline phase. FIG. 2B illustrates the protective coating 200 ofFIG. 2A after an optional annealing and oxidation process. For example,the optional annealing and oxidation process may be performed when thefirst deposited layer 204 is deposited in the amorphous phase. Theoxidizing process may partially oxidize the protective coating 200.

Following the optional annealing and oxidation process, the protectivecoating 200 comprises an intermediate region 206 disposed between thefirst deposited layer 204 and the aerospace component 202. Theintermediate region 206 is an aluminum depleted region of the aerospacecomponent 202, or a region depleted of an aluminum-rich phase. Theintermediate region 206 may not be a distinct layer, but may instead bea topmost portion or region of the aerospace component 202. Aluminumfrom the aerospace component 202 diffuses into the first deposited layer204, adding an additional amount of aluminum oxide (not shown) to thefirst deposited layer 204. The additional amount of aluminum oxide andthe first deposited layer 204 form a coalesced layer 208 having apreferred crystalline assembly. Thus, after the annealing process ofFIG. 2B, the first deposited layer 204 has a greater amount of aluminumoxide. The protective coating 200 protects the aerospace component 202from corrosion and oxidation, and further decreases the rate ofdepletion of aluminum from the intermediate region 206. Performing theoptional annealing and oxidizing process may further enhance andstrengthen the protective properties of the protective coating 200.

FIG. 3A illustrates a protective coating 300 or nanolaminate film stackdeposited on an aerospace component 302. The aerospace component 302comprises a nickel alloy comprising aluminum. The protective component300 comprises a first deposited layer 310A comprising chromium, such aschromium oxide (Cr₂O₃). The first deposited layer 310A may be depositedin an amorphous phase or a crystalline phase. FIG. 3B illustrates theprotective coating 300 of FIG. 3A after an optional annealing andoxidation process. For example, the optional annealing and oxidationprocess may be performed when the first deposited layer 310A isdeposited in the amorphous phase. The oxidizing process may partiallyoxidize the protective coating 300. The protective coating 300 comprisesa coalesced film or layer 308 formed during the annealing and oxidizingprocess, the coalesced layer 308 comprising a chromium oxide region 310Bfrom the first deposited layer 310A. The coalesced layer 308 is in apreferred crystalline phase.

Following the annealing and oxidizing process, an intermediate region306 is disposed between the coalesced layer 308 and the aerospacecomponent 302. The intermediate region 306 is an aluminum depletedregion of the aerospace component 302, or a region depleted of analuminum-rich phase. The intermediate region 306 may not be a distinctlayer, but may instead be a topmost portion or region of the aerospacecomponent 302. Aluminum from the aerospace component 302 diffuses intothe coalesced layer 308, forming a thin region 314 of aluminum oxide inthe coalesced layer 308 above the intermediate region 306. The coalescedlayer 308 further comprises a mixed chromium-aluminum region 312, suchas chromium-aluminum oxide ((Al, Cr)₂O₃), disposed between the aluminumoxide region 310 and the chromium oxide region 310B, each region beingin a crystalline phase. While the regions 310B, 312, 314 of thecoalesced layer 308 are shown as distinct regions or layers, thecoalesced layer 308 is one, substantially continuous layer comprisingeach of the elements of the regions 310B, 312, 314 (i.e., aluminumoxide, chromium oxide, and mixed chromium-aluminum oxide). Theprotective coating 300 protects the aerospace component 302 fromcorrosion and oxidation, and further decreases the rate of depletion ofaluminum from the intermediate region 306. Performing the optionalannealing and oxidizing process may further enhance and strengthen theprotective properties of the protective coating 300.

FIG. 4A illustrates a protective coating 400 or nanolaminate film stackdeposited on an aerospace component 402. The aerospace component 402comprises a nickel alloy comprising aluminum. The protective component400 comprises a first deposited layer 404A comprising aluminum, such asaluminum oxide, and a second deposited layer 410A comprising chromium,such as chromium oxide, disposed on the first deposited layer 404A. Thefirst deposited layer 404A and the second deposited layer 410A may eachbe deposited in an amorphous phase or a crystalline phase. FIG. 4Billustrates the protective coating 400 of FIG. 4A after an optionalannealing and oxidation process. For example, the optional annealing andoxidation process may be performed when the first deposited layer 404Aand/or the second deposited layer 410A are deposited in the amorphousphase. The oxidizing process may partially oxidize the protectivecoating 400. The protective coating 400 includes a coalesced film orlayer 408 formed during the annealing and oxidizing process, thecoalesced layer 408 comprising an aluminum oxide region 404B from thefirst deposited layer 404A and a chromium oxide region 410B from thesecond deposited layer 410A. The coalesced layer 408 is in a preferredcrystalline phase.

In one embodiment, the first deposited layer 404A may be deposited, andthen annealed and oxidized to convert the first deposited layer 404A tothe preferred crystalline phase. The second deposited layer 410A maythen be deposited on the first deposited layer 404A, and then annealedand oxidized to convert the second deposited layer 410A to the preferredcrystalline phase.

Following the annealing and oxidizing process, an intermediate region406 is disposed between the coalesced layer 408 and the aerospacecomponent 402. The intermediate region 406 is an aluminum depletedregion of the aerospace component 402, or a region depleted of analuminum-rich phase. The intermediate region 406 may not be a distinctlayer, but may instead be a topmost portion or region of the aerospacecomponent 402. Aluminum from the aerospace component 402 diffuses intothe coalesced layer 408, adding an additional amount of aluminum oxideto the aluminum oxide region 404B of the coalesced layer 408 above theintermediate region 406. The coalesced layer 408 further comprises amixed chromium-aluminum region 412, such as chromium-aluminum oxide,disposed between the aluminum oxide region 404B and the chromium oxideregion 410B, each region being in a crystalline phase. While the regions404B, 412, 410B of the coalesced layer 408 are shown as distinct regionsor layers, the coalesced layer 408 is one, substantially continuouslayer comprising each of the elements of the regions 404B, 412, 410B(i.e., aluminum oxide, chromium oxide, and mixed chromium-aluminumoxide). The protective coating 400 protects the aerospace component 402from corrosion and oxidation, and further decreases the rate ofdepletion of aluminum from the intermediate region 406. Performing theoptional annealing and oxidizing process may further enhance andstrengthen the protective properties of the protective coating 400.

FIG. 5A illustrates a protective coating 500 or nanolaminate film stackdeposited on an aerospace component 502. The aerospace component 502comprises a nickel alloy comprising aluminum. The protective component500 comprises a first deposited layer 504A comprising aluminum (e.g.,aluminum oxide), a second deposited layer 516 comprising chromium (e.g.,chromium oxide) disposed on the first deposited layer 504A, a thirddeposited layer 518 comprising aluminum (e.g., aluminum oxide) disposedon the second deposited layer 516, a fourth deposited layer 520comprising chromium (e.g., chromium oxide) disposed on the thirddeposited layer 518, and a fifth deposited layer 522 comprising aluminum(e.g., aluminum oxide) disposed on the fourth deposited layer 520. Eachof the deposited layers 504A, 516, 518, 520, 522 may be deposited in anamorphous phase or a crystalline phase. The first deposited layer 504Amay have a greater thickness than each of the second through fifthdeposited layers 516-522. The second through fifth deposited layers516-522 may have about the same thickness. While five deposited layersare shown, any number of layers may be utilized.

FIG. 5B illustrates the protective component 500 of FIG. 5A after anoptional annealing and oxidation process. For example, the optionalannealing and oxidation process may be performed when one or more of thedeposited layers 504A, 516, 518, 520, 522 are deposited in the amorphousphase. The oxidizing process may partially oxidize the protectivecoating 500. In one embodiment, the first deposited layer 504A may bedeposited, and then annealed and oxidized to convert the first depositedlayer 504A to the preferred crystalline phase. The second depositedlayer 516 may then be deposited on the first deposited layer 504A, andthen annealed and oxidized to convert the second deposited layer 516 tothe preferred crystalline phase. The third deposited layer 518 may thenbe deposited on the second deposited layer 516, and then annealed andoxidized to convert the third deposited layer 518 to the preferredcrystalline phase. The fourth deposited layer 520 may then be depositedon the third deposited layer 518, and then annealed and oxidized toconvert the fourth deposited layer 520 to the preferred crystallinephase. The fifth deposited layer 522 may then be deposited on the fourthdeposited layer 520, and then annealed and oxidized to convert the fifthdeposited layer 522 to the preferred crystalline phase.

The protective coating 500 comprises a coalesced film or layer 508formed during the annealing and oxidizing process, the coalesced layer508 comprising an aluminum oxide region 504B from the first depositedlayer 504A and a mixed chromium-aluminum region 512, such aschromium-aluminum oxide. The coalesced layer 508 is in a preferredcrystalline phase. An intermediate region 506 is disposed between thecoalesced layer 508 and the aerospace component 502. The intermediateregion 506 is an aluminum depleted region of the aerospace component502, or a region depleted of an aluminum-rich phase. The intermediateregion 506 may not be a distinct layer, but may instead be a topmostportion or region of the aerospace component 502. Aluminum from theaerospace component 502 diffuses into the coalesced layer 508, adding anadditional amount of aluminum oxide to the aluminum oxide region 504B ofthe coalesced layer 508 above the intermediate region 506. While theregions 504B and 512 of the coalesced layer 508 are shown as distinctregions or layers, the coalesced layer 508 is one, substantiallycontinuous layer comprising each of the elements of the regions 504B,512 (i.e., aluminum oxide, and mixed chromium-aluminum oxide). Theprotective coating 500 protects the aerospace component 502 fromcorrosion and oxidation, and further decreases the rate of depletion ofaluminum from the intermediate region 506. Performing the optionalannealing and oxidizing process may further enhance and strengthen theprotective properties of the protective coating 500.

FIG. 6A illustrates a protective coating 600 or nanolaminate film stackdeposited on an aerospace component 602. The aerospace component 602comprises a nickel alloy comprising aluminum. The protective component600 comprises a first deposited layer 624 comprising hafnium (e.g.,hafnium doped aluminum oxide), a second deposited layer 616 comprisingchromium (e.g., chromium oxide) disposed on the first deposited layer624, a third deposited layer 618 comprising aluminum (e.g., aluminumoxide) disposed on the second deposited layer 616, a fourth depositedlayer 620 comprising chromium (e.g., chromium oxide) disposed on thethird deposited layer 618, and a fifth deposited layer 622 comprisingaluminum (e.g., aluminum oxide) disposed on the fourth deposited layer620. Each of the deposited layers 624, 616, 618, 620, 622 may bedeposited in an amorphous phase or a crystalline phase. The firstdeposited layer 624 may have a greater thickness than each of the secondthrough fifth deposited layers 616-622. The second through fifthdeposited layers 616-622 may have about the same thickness. While fivedeposited layers are shown, any number of layers may be utilized.

FIG. 6B illustrates the protective coating 600 of FIG. 6A after anoptional annealing and oxidation process. For example, the optionalannealing and oxidation process may be performed when one or more of thedeposited layers 624, 616, 618, 620, 622 are deposited in the amorphousphase. The oxidizing process may partially oxidize the protectivecoating 600. In one embodiment, the first deposited layer 624 may bedeposited, and then annealed and oxidized to convert the first depositedlayer 624 to the preferred crystalline phase. The second deposited layer616 may then be deposited on the first deposited layer 624, and thenannealed and oxidized to convert the second deposited layer 616 to thepreferred crystalline phase. The third deposited layer 618 may then bedeposited on the second deposited layer 616, and then annealed andoxidized to convert the third deposited layer 618 to the preferredcrystalline phase. The fourth deposited layer 620 may then be depositedon the third deposited layer 618, and then annealed and oxidized toconvert the fourth deposited layer 620 to the preferred crystallinephase. The fifth deposited layer 622 may then be deposited on the fourthdeposited layer 620, and then annealed and oxidized to convert the fifthdeposited layer 622 to the preferred crystalline phase.

The protective coating 600 comprises a coalesced film or layer 608formed during the annealing and oxidizing process disposed on the firstdeposited layer 624, the coalesced layer 608 comprising a mixedchromium-aluminum compound, such as chromium-aluminum oxide. Thecoalesced layer 608 is in a preferred crystalline phase. An intermediateregion 606 is disposed between the coalesced layer 608 and the aerospacecomponent 602. The intermediate region 606 is an aluminum depletedregion of the aerospace component 602, or a region depleted of analuminum-rich phase. The intermediate region 606 may not be a distinctlayer, but may instead be a topmost portion or region of the aerospacecomponent 602. Aluminum from the aerospace component 602 diffuses intothe first deposited layer 624, adding an additional amount of aluminumoxide to the first deposited layer 624 above the intermediate region606. The protective coating 600 protects the aerospace component 602from corrosion and oxidation, and further decreases the rate ofdepletion of aluminum from the intermediate region 606. Performing theoptional annealing and oxidizing process may further enhance andstrengthen the protective properties of the protective coating 600.

At block 110, prior to producing a protective coating 200, 300, 400,500, 600, the aerospace component 202, 302, 402, 502, 602 can optionallybe exposed to one or more pre-clean processes. The surfaces of theaerospace component 202, 302, 402, 502, 602 can contain oxides,organics, oil, soil, particulate, debris, and/or other contaminants thatmay be removed prior to producing the protective coating 200, 300, 400,500, 600 on the aerospace component 202, 302, 402, 502, 602. Thepre-clean process can be or include one or more basting or texturingprocesses, vacuum purges, solvent clean, acid clean, wet clean, plasmaclean, sonication, or any combination thereof. Once cleaned and/ortextured, the subsequently deposited protective coating 200, 300, 400,500, 600 has stronger adhesion to the surfaces of the aerospacecomponent 202, 302, 402, 502, 602 than if otherwise not exposed to thepre-clean process.

In one or more examples, the surfaces of the aerospace component 202,302, 402, 502, 602 can be blasted with or otherwise exposed to beads,sand, carbonate, or other particulates to remove oxides and othercontaminates therefrom and/or to provide texturing to the surfaces ofthe aerospace component 202, 302, 402, 502, 602. In some examples, theaerospace component 202, 302, 402, 502, 602 can be placed into a chamberwithin a pulsed push-pull system and exposed to cycles of purge gas(e.g., N₂, Ar, He, or any combination thereof) and vacuum purges toremove debris from small holes on the aerospace component 202, 302, 402,502, 602. In other examples, the surfaces of the aerospace component202, 302, 402, 502, 602 can be exposed to hydrogen plasma, oxygen orozone plasma, and/or nitrogen plasma, which can be generated in a plasmachamber or by a remote plasma system.

In one or more examples, such as for organic removal or oxide removal,the surfaces of the aerospace component 202, 302, 402, 502, 602 can beexposed to a hydrogen plasma, then degassed, then exposed to ozonetreatment. In other examples, such as for organic removal, the surfacesof the aerospace component 202, 302, 402, 502, 602 can be exposed to awet clean that includes: soaking in an alkaline degreasing solution,rinsing, exposing the surfaces to an acid clean (e.g., sulfuric acid,phosphoric acid, or hydrochloric acid), rinsing, and exposing thesurfaces deionized water sonication bath. In some examples, such as foroxide removal, the surfaces of the aerospace component 202, 302, 402,502, 602 can be exposed to a wet clean that includes: exposing thesurfaces to a dilute acid solution (e.g., acetic acid or hydrochloricacid), rinsing, and exposing the surfaces deionized water sonicationbath. In one or more examples, such as for particle removal, thesurfaces of the aerospace component 202, 302, 402, 502, 602 can beexposed to sonication (e.g., megasonication) and/or a supercriticalcarbon dioxide wash, followed by exposing to cycles of purge gas (e.g.,N₂, Ar, He, or any combination thereof) and vacuum purges to removeparticles from and dry the surfaces. In some examples, the aerospacecomponent 202, 302, 402, 502, 602 can be exposed to heating or dryingprocesses, such as heating the aerospace component 202, 302, 402, 502,602 to a temperature of about 50° C., about 65° C., or about 80° C. toabout 100° C., about 120° C., or about 150° C. and exposing to surfacesto the purge gas. The aerospace component 202, 302, 402, 502, 602 can beheated in an oven or exposed to lamps for the heating or dryingprocesses.

At block 120, the aerospace component 202, 302, 402, 502, or 602 isexposed to a first precursor and a first reactant to form the firstdeposited layer 204, 310A, 404A, 504A, or 624 on the aerospace component202, 302, 402, 502, 602 by a vapor deposition process, as depicted inFIGS. 2A, 3A, 4A, 5A, and 6A, respectively, to form a protective coating200, 300, 400, 500, 600. The vapor deposition process can be an ALDprocess, a plasma-enhanced ALD (PE-ALD) process, a thermal chemicalvapor deposition (CVD) process, a plasma-enhanced CVD (PE-CVD) process,a low pressure CVD process, or any combination thereof.

In one or more embodiments, the vapor deposition process is an ALDprocess and the method includes sequentially exposing the surface of theaerospace component 202, 302, 402, 502, or 602 to the first precursorand the first reactant to form the first deposited layer 204, 310A,404A, 504A, or 624. Each cycle of the ALD process includes exposing thesurface of the aerospace component to the first precursor, conducting apump-purge, exposing the aerospace component to the first reactant, andconducting a pump-purge to form the first deposited layer 204, 310A,404A, 504A, or 624. The order of the first precursor and the firstreactant can be reversed, such that the ALD cycle includes exposing thesurface of the aerospace component to the first reactant, conducting apump-purge, exposing the aerospace component to the first precursor, andconducting a pump-purge to form the first deposited layer 204, 310A,404A, 504A, or 624.

In some examples, during each ALD cycle, the aerospace component 202,302, 402, 502, 602 is exposed to the first precursor for about 0.1seconds to about 10 seconds, the first reactant for about 0.1 seconds toabout 10 seconds, and the pump-purge for about 0.5 seconds to about 30seconds. In other examples, during each ALD cycle, the aerospacecomponent 202, 302, 402, 502, 602 is exposed to the first precursor forabout 0.5 seconds to about 3 seconds, the first reactant for about 0.5seconds to about 3 seconds, and the pump-purge for about 1 second toabout 10 seconds. The ALD process may be performed at a temperature ofabout 20° C. to about 500° C., such as about 300° C.

Each ALD cycle is repeated from 2, 3, 4, 5, 6, 8, about 10, about 12, orabout 15 times to about 18, about 20, about 25, about 30, about 40,about 50, about 65, about 80, about 100, about 120, about 150, about200, about 250, about 300, about 350, about 400, about 500, about 800,about 1,000, or more times to form the first deposited layer. Forexample, each ALD cycle is repeated from 2 times to about 1,000 times, 2times to about 800 times, 2 times to about 500 times, 2 times to about300 times, 2 times to about 250 times, 2 times to about 200 times, 2times to about 150 times, 2 times to about 120 times, 2 times to about100 times, 2 times to about 80 times, 2 times to about 50 times, 2 timesto about 30 times, 2 times to about 20 times, 2 times to about 15 times,2 times to about 10 times, 2 times to 5 times, about 8 times to about1,000 times, about 8 times to about 800 times, about 8 times to about500 times, about 8 times to about 300 times, about 8 times to about 250times, about 8 times to about 200 times, about 8 times to about 150times, about 8 times to about 120 times, about 8 times to about 100times, about 8 times to about 80 times, about 8 times to about 50 times,about 8 times to about 30 times, about 8 times to about 20 times, about8 times to about 15 times, about 8 times to about 10 times, about 20times to about 1,000 times, about 20 times to about 800 times, about 20times to about 500 times, about 20 times to about 300 times, about 20times to about 250 times, about 20 times to about 200 times, about 20times to about 150 times, about 20 times to about 120 times, about 20times to about 100 times, about 20 times to about 80 times, about 20times to about 50 times, about 20 times to about 30 times, about 50times to about 1,000 times, about 50 times to about 500 times, about 50times to about 350 times, about 50 times to about 300 times, about 50times to about 250 times, about 50 times to about 150 times, or about 50times to about 100 times to form the first deposited layer 204, 310A,404A, 504A, or 624.

In other embodiments, the vapor deposition process is a CVD process andthe method includes simultaneously exposing the aerospace component 202,302, 402, 502, or 602 to the first precursor and the first reactant toform the first deposited layer 204, 310A, 404A, 504A, 624. The CVDprocess may be performed at a temperature of about 300° C. to about1200° C. The CVD process may be performed at a higher temperature thanthe ALD process. For example, the ALD process may be performed at atemperature of about 500° C. and the CVD process may be performed at atemperature of about 1100° C. The CVD process may be a PECVD processperformed at a temperature of about 300° C. to about 1100° C., a lowpressure CVD process performed at a temperature of about 500° C. toabout 1100° C., or a thermal CVD process performed at a temperature ofabout 500° C. to about 1100° C. Depositing the first deposited layer204, 310A, 404A, 504A, 624 by a CVD process may convert the firstdeposited layer 204, 310A, 404A, 504A, 624 to a crystalline phase. Assuch, the protective coating 200, 300, 400, 500, 600 may not need toundergo the annealing and oxidation process. However, the firstdeposited layer 204, 310A, 404A, 504A, 624 deposited through a CVDprocess may need to undergo the annealing and oxidation process toconvert the first deposited layer 204, 310A, 404A, 504A, 624 to thepreferred crystalline assembly.

During an ALD process or a CVD process, each of the first precursor andthe first reactant can independent include one or more carrier gases.One or more purge gases can be flowed across the aerospace componentand/or throughout the processing chamber in between the exposures of thefirst precursor and the first reactant. In some examples, the same gasmay be used as a carrier gas and a purge gas. Exemplary carrier gasesand purge gases can independently be or include one or more of nitrogen(N₂), argon, helium, neon, hydrogen (H₂), or any combination thereof.

The first deposited layer 204, 310A, 404A, 504A, or 624 can have athickness of about 0.1 nm, about 0.2 nm, about 0.3 nm, about 0.4 nm,about 0.5 nm, about 0.8 nm, about 1 nm, about 2 nm, about 3 nm, about 5nm, about 8 nm, about 10 nm, about 12 nm, or about 15 nm to about 18 nm,about 20 nm, about 25 nm, about 30 nm, about 40 nm, about 50 nm, about60 nm, about 80 nm, about 100 nm, about 120 nm, or about 150 nm. Forexample, the first deposited layer 204, 310A, 404A, 504A, or 624 canhave a thickness of about 0.1 nm to about 150 nm, about 0.2 nm to about150 nm, about 0.2 nm to about 120 nm, about 0.2 nm to about 100 nm,about 0.2 nm to about 80 nm, about 0.2 nm to about 50 nm, about 0.2 nmto about 40 nm, about 0.2 nm to about 30 nm, about 0.2 nm to about 20nm, about 0.2 nm to about 10 nm, about 0.2 nm to about 5 nm, about 0.2nm to about 1 nm, about 0.2 nm to about 0.5 nm, about 0.5 nm to about150 nm, about 0.5 nm to about 120 nm, about 0.5 nm to about 100 nm,about 0.5 nm to about 80 nm, about 0.5 nm to about 50 nm, about 0.5 nmto about 40 nm, about 0.5 nm to about 30 nm, about 0.5 nm to about 20nm, about 0.5 nm to about 10 nm, about 0.5 nm to about 5 nm, about 0.5nm to about 1 nm, about 2 nm to about 150 nm, about 2 nm to about 120nm, about 2 nm to about 100 nm, about 2 nm to about 80 nm, about 2 nm toabout 50 nm, about 2 nm to about 40 nm, about 2 nm to about 30 nm, about2 nm to about 20 nm, about 2 nm to about 10 nm, about 2 nm to about 5nm, about 2 nm to about 3 nm, about 10 nm to about 150 nm, about 10 nmto about 120 nm, about 10 nm to about 100 nm, about 10 nm to about 80nm, about 10 nm to about 50 nm, about 10 nm to about 40 nm, about 10 nmto about 30 nm, about 10 nm to about 20 nm, or about 10 nm to about 15nm.

In one or more embodiments, the first precursor contains one or morechromium precursors, such as in FIG. 3A, one or more aluminumprecursors, such as in FIGS. 2A, 4A, and 5A, or one or more hafniumprecursors, such as in FIG. 6A. The first reactant contains one or morereducing agents, one or more oxidizing agents, one or more nitridingagents, one or more silicon precursors, one or more carbon precursors,or any combination thereof. In some examples, such as FIG. 3A, the firstdeposited layer 310A is a chromium-containing layer which can be orinclude metallic chromium, chromium oxide, chromium nitride, chromiumsilicide, chromium carbide, or any combination thereof. In otherexamples, such as FIGS. 2A, 4A, 5A, and 6A, the first deposited layer204, 404A, 504A, or 624 is an aluminum-containing layer which can be orinclude metallic aluminum, aluminum oxide, aluminum nitride, aluminumsilicide, aluminum carbide, or any combination thereof. In furtherexamples, such as FIG. 6A, the first deposited layer 624 is ahafnium-containing layer which can be or include hafnium doped aluminumoxide, metallic hafnium, hafnium oxide, hafnium nitride, hafniumsilicide, hafnium carbide, or any combination thereof.

The chromium precursor can be or include one or more of chromiumcyclopentadiene compounds, chromium carbonyl compounds, chromiumacetylacetonate compounds, chromium diazadienyl compounds, substitutesthereof, complexes thereof, abducts thereof, salts thereof, or anycombination thereof. Exemplary chromium precursor can be or includebis(cyclopentadiene) chromium (Cp₂Cr), bis(pentamethylcyclopentadiene)chromium ((Me₅Cp)₂Cr), bis(isoproplycyclopentadiene) chromium((iPrCp)₂Cr), bis(ethylbenzene) chromium ((EtBz)₂Cr), chromiumhexacarbonyl (Cr(CO)₆), chromium acetylacetonate (Cr(acac)₃, also knownas, tris(2,4-pentanediono) chromium), chromium hexafluoroacetylacetonate(Cr(hfac)₃), chromium(III) tris(2,2,6,6-tetramethyl-3,5-heptanedionate){Cr(tmhd)₃}, chromium(II) bis(1,4-ditertbutyldiazadienyl), isomersthereof, complexes thereof, abducts thereof, salts thereof, or anycombination thereof. Exemplary chromium diazadienyl compounds can have achemical formula of:

where each R and R′ is independently selected from H, C1-C6 alkyl, aryl,acyl, alkylamido, hydrazido, silyl, aldehyde, keto, C2-C4 alkenyl,alkynyl, or substitutes thereof. In some examples, each R isindependently a C1-C6 alkyl which is selected from methyl, ethyl,propyl, butyl, or isomers thereof, and R′ is H. For example, R is metyland R′ is H, R is ethyl and R′ is H, R is iso-propyl and R′ is H, or Ris tert-butyl and R′ is H.

The aluminum precursor can be or include one or more of aluminum alkylcompounds, one or more of aluminum alkoxy compounds, one or more ofaluminum acetylacetonate compounds, substitutes thereof, complexesthereof, abducts thereof, salts thereof, or any combination thereof.Exemplary aluminum precursors can be or include trimethylaluminum,triethylaluminum, tripropylaluminum, tributylaluminum,trimethoxyaluminum, triethoxyaluminum, tripropoxyaluminum,tributoxyaluminum, aluminum acetylacetonate (Al(acac)₃, also known as,tris(2,4-pentanediono) aluminum), aluminum hexafluoroacetylacetonate(Al(hfac)₃), trisdipivaloylmethanatoaluminum (DPM₃Al; (C₁₁H₁₉O₂)₃Al),isomers thereof, complexes thereof, abducts thereof, salts thereof, orany combination thereof.

The hafnium precursor can be or include one or more of hafniumcyclopentadiene compounds, one or more of hafnium amino compounds, oneor more of hafnium alkyl compounds, one or more of hafnium alkoxycompounds, substitutes thereof, complexes thereof, abducts thereof,salts thereof, or any combination thereof. Exemplary hafnium precursorscan be or include bis(methylcyclopentadiene) dimethylhafnium((MeCp)₂HfMe₂), bis(methylcyclopentadiene) methylmethoxyhafnium((MeCp)₂Hf(OMe)(Me)), bis(cyclopentadiene) dimethylhafnium ((Cp)₂HfMe₂),tetra(tert-butoxy) hafnium, hafniumum isopropoxide ((iPrO)₄Hf),tetrakis(dimethylamino) hafnium (TDMAH), tetrakis(diethylamino) hafnium(TDEAH), tetrakis(ethylmethylamino) hafnium (TEMAH), isomers thereof,complexes thereof, abducts thereof, salts thereof, or any combinationthereof.

The titanium precursor can be or include one or more of titaniumcyclopentadiene compounds, one or more of titanium amino compounds, oneor more of titanium alkyl compounds, one or more of titanium alkoxycompounds, substitutes thereof, complexes thereof, abducts thereof,salts thereof, or any combination thereof. Exemplary titanium precursorscan be or include bis(methylcyclopentadiene) dimethyltitanium((MeCp)₂TiMe₂), bis(methylcyclopentadiene) methylmethoxytitanium((MeCp)₂Ti(OMe)(Me)), bis(cyclopentadiene) dimethyltitanium((Cp)₂TiMe₂), tetra(tert-butoxy) titanium, titaniumum isopropoxide((iPrO)₄Ti), tetrakis(dimethylamino) titanium (TDMAT),tetrakis(diethylamino) titanium (TDEAT), tetrakis(ethylmethylamino)titanium (TEMAT), isomers thereof, complexes thereof, abducts thereof,salts thereof, or any combination thereof.

In one or more examples, the first deposited layer 310A is achromium-containing layer which can be or include metallic chromium andthe first reactant contains one or more reducing agents. In someexamples, the first deposited layer 204, 404A, 504A, or 624 is analuminum-containing layer which can be or include metallic aluminum andthe first reactant contains one or more reducing agents. In otherexamples, the first deposited layer 624 is a hafnium-containing layerwhich can be or include metallic hafnium and the first reactant containsone or more reducing agents. Exemplary reducing agents can be or includehydrogen (H₂), ammonia, hydrazine, one or more hydrazine compounds, oneor more alcohols, a cyclohexadiene, a dihydropyrazine, an aluminumcontaining compound, abducts thereof, salts thereof, plasma derivativesthereof, or any combination thereof.

In some examples, the first deposited layer 310A is achromium-containing layer which can be or include chromium oxide and thefirst reactant contains one or more oxidizing agents. In other examples,the first deposited layer 204, 404A, 504A, or 624 is analuminum-containing layer which can be or include aluminum oxide and thefirst reactant contains one or more oxidizing agents. In furtherexamples, the first deposited layer 624 is a hafnium-containing layerwhich can be or include hafnium oxide and the first reactant containsone or more oxidizing agents. Exemplary oxidizing agents can be orinclude water (e.g., steam), oxygen (O₂), atomic oxygen, ozone, nitrousoxide, one or more peroxides, one or more alcohols, plasmas thereof, orany combination thereof.

In one or more examples, the first deposited layer 310A is achromium-containing layer which can be or include chromium nitride andthe first reactant contains one or more nitriding agents. In otherexamples, the first deposited layer 204, 404A, 504A, or 624 is analuminum-containing layer which can be or include aluminum nitride andthe first reactant contains one or more nitriding agents. In someexamples, the first deposited layer 624 is a hafnium-containing layerwhich can be or include hafnium nitride and the first reactant containsone or more nitriding agents. Exemplary nitriding agents can be orinclude ammonia, atomic nitrogen, one or more hydrazines, nitric oxide,plasmas thereof, or any combination thereof.

In one or more examples, the first deposited layer 310A is achromium-containing layer which can be or include chromium silicide andthe first reactant contains one or more silicon precursors. In someexamples, the first deposited layer 204, 404A, 504A, or 624 is analuminum-containing layer which can be or include aluminum silicide andthe first reactant contains one or more silicon precursors. In otherexamples, the first deposited layer 624 is a hafnium-containing layerwhich can be or include hafnium silicide and the first reactant containsone or more silicon precursors. Exemplary silicon precursors can be orinclude silane, disilane, trisilane, tetrasilane, pentasilane,hexasilane, monochlorosilane, dichlorosilane, trichlorosilane,tetrachlorosilane, hexachlorosilane, substituted silanes, plasmaderivatives thereof, or any combination thereof.

In some examples, the first deposited layer 310A is achromium-containing layer which can be or include chromium carbide andthe first reactant contains one or more carbon precursors. In otherexamples, the first deposited layer 204, 404A, 504A, or 624 is analuminum-containing layer which can be or include aluminum carbide andthe first reactant contains one or more carbon precursors. In furtherexamples, the first deposited layer 624 is a hafnium-containing layerwhich can be or include hafnium carbide and the first reactant containsone or more carbon precursors. Exemplary carbon precursors can be orinclude one or more alkanes, one or more alkenes, one or more alkynes,substitutes thereof, plasmas thereof, or any combination thereof.

At block 130, the aerospace component 402, 502, 602 is optionallyexposed to a second precursor and a second reactant to form the seconddeposited layer 410A, 516, or 616 on the first deposited layer 404A,504A, or 624 to add to the protective coating 400, 500, 600, as shown inFIGS. 4A, 5A, and 6A. The first deposited layer 404A, 504A, or 624 orFIGS. 4A, 5A, and 6A and second deposited layer 410A, 516, 616 or FIGS.4A, 5A, and 6A, respectively, have different compositions from eachother. In some examples, the first precursor is a different precursorthan the second precursor, such as that the first precursor is a sourceof a first type of metal and the second precursor is a source of asecond type of metal and the first and second types of metal aredifferent. While FIG. 2A and FIG. 3A are not shown with a seconddeposited layer, the protective coatings 200, 300 may include one ormore second deposited layers having a different composition than thefirst deposited layers 204, 310A.

In one or more embodiments, the second precursor is or includes one ormore aluminum precursors or one or more chromium precursors; however,the second precursor can be or include one or more aluminum precursors,one or more chromium precursors, one or more hafnium precursors, one ormore yttrium precursors, or any combination thereof. The second reactantcan be any other reactants used as the first reactant. For example, thesecond reactant can be or include one or more reducing agents, one ormore oxidizing agents, one or more nitriding agents, one or more siliconprecursors, one or more carbon precursors, or any combination thereof,as described and discussed above. During the ALD process, each of thesecond precursor and the second reactant can independent include one ormore carrier gases. One or more purge gases can be flowed across theaerospace component and/or throughout the processing chamber in betweenthe exposures of the second precursor and the second reactant. In someexamples, the same gas may be used as a carrier gas and a purge gas.Exemplary carrier gases and purge gases can independently be or includeone or more of nitrogen (N₂), argon, helium, neon, hydrogen (H₂), or anycombination thereof.

In one or more embodiments, the second deposited layer 410A, 516, 616contains chromium oxide or aluminum oxide; however, the second depositedlayer 410A, 516, 616 may contain aluminum nitride, silicon oxide,silicon nitride, silicon carbide, yttrium oxide, yttrium nitride,yttrium silicon nitride, hafnium oxide, hafnium nitride, hafniumsilicide, hafnium silicate, titanium oxide, titanium nitride, titaniumsilicide, titanium silicate, or any combination thereof. In one or moreexamples, if the first deposited layer 204, 310A, 404A, 504A, or 624contains aluminum oxide or aluminum nitride, then the second depositedlayer 410A, 516, 616 does not contain aluminum oxide or aluminumnitride. Similarly, if the first deposited layer 204, 310A, 404A, 504A,or 624 contains chromium oxide or chromium nitride, then the seconddeposited layer 410A, 516, 616 does not contain chromium oxide orchromium nitride. If the first deposited layer 204, 310A, 404A, 504A, or624 contains hafnium oxide or hafnium nitride, then the second depositedlayer 410A, 516, 616 does not contain hafnium oxide or hafnium nitride.

Each cycle of the ALD process includes exposing the aerospace componentto the second precursor, conducting a pump-purge, exposing the aerospacecomponent to the second reactant, and conducting a pump-purge to formthe second deposited layer 410A, 516, 616. The order of the secondprecursor and the second reactant can be reversed, such that the ALDcycle includes exposing the surface of the aerospace component to thesecond reactant, conducting a pump-purge, exposing the aerospacecomponent to the second precursor, and conducting a pump-purge to formthe second deposited layer 410A, 516, 616.

In one or more examples, during each ALD cycle, the aerospace component402, 502, 602 is exposed to the second precursor for about 0.1 secondsto about 10 seconds, the second reactant for about 0.1 seconds to about10 seconds, and the pump-purge for about 0.5 seconds to about 30seconds. In other examples, during each ALD cycle, the aerospacecomponent 402, 502, 602 is exposed to the second precursor for about 0.5seconds to about 3 seconds, the second reactant for about 0.5 seconds toabout 3 seconds, and the pump-purge for about 1 second to about 10seconds. The ALD process may be performed at a temperature of about 20°C. to about 500° C., such as about 300° C.

Each ALD cycle is repeated from 2, 3, 4, 5, 6, 8, about 10, about 12, orabout 15 times to about 18, about 20, about 25, about 30, about 40,about 50, about 65, about 80, about 100, about 120, about 150, about200, about 250, about 300, about 350, about 400, about 500, about 800,about 1,000, or more times to form the second deposited layer 410A, 516,616. For example, each ALD cycle is repeated from 2 times to about 1,000times, 2 times to about 800 times, 2 times to about 500 times, 2 timesto about 300 times, 2 times to about 250 times, 2 times to about 200times, 2 times to about 150 times, 2 times to about 120 times, 2 timesto about 100 times, 2 times to about 80 times, 2 times to about 50times, 2 times to about 30 times, 2 times to about 20 times, 2 times toabout 15 times, 2 times to about 10 times, 2 times to 5 times, about 8times to about 1,000 times, about 8 times to about 800 times, about 8times to about 500 times, about 8 times to about 300 times, about 8times to about 250 times, about 8 times to about 200 times, about 8times to about 150 times, about 8 times to about 120 times, about 8times to about 100 times, about 8 times to about 80 times, about 8 timesto about 50 times, about 8 times to about 30 times, about 8 times toabout 20 times, about 8 times to about 15 times, about 8 times to about10 times, about 20 times to about 1,000 times, about 20 times to about800 times, about 20 times to about 500 times, about 20 times to about300 times, about 20 times to about 250 times, about 20 times to about200 times, about 20 times to about 150 times, about 20 times to about120 times, about 20 times to about 100 times, about 20 times to about 80times, about 20 times to about 50 times, about 20 times to about 30times, about 50 times to about 1,000 times, about 50 times to about 500times, about 50 times to about 350 times, about 50 times to about 300times, about 50 times to about 250 times, about 50 times to about 150times, or about 50 times to about 100 times to form the second depositedlayer 410A, 516, 616.

The second deposited layer 410A, 516, 616 can have a thickness of about0.1 nm, about 0.2 nm, about 0.3 nm, about 0.4 nm, about 0.5 nm, about0.8 nm, about 1 nm, about 2 nm, about 3 nm, about 5 nm, about 8 nm,about 10 nm, about 12 nm, or about 15 nm to about 18 nm, about 20 nm,about 25 nm, about 30 nm, about 40 nm, about 50 nm, about 60 nm, about80 nm, about 100 nm, about 120 nm, or about 150 nm. For example, thesecond deposited layer 410A, 516, 616 can have a thickness of about 0.1nm to about 150 nm, about 0.2 nm to about 150 nm, about 0.2 nm to about120 nm, about 0.2 nm to about 100 nm, about 0.2 nm to about 80 nm, about0.2 nm to about 50 nm, about 0.2 nm to about 40 nm, about 0.2 nm toabout 30 nm, about 0.2 nm to about 20 nm, about 0.2 nm to about 10 nm,about 0.2 nm to about 5 nm, about 0.2 nm to about 1 nm, about 0.2 nm toabout 0.5 nm, about 0.5 nm to about 150 nm, about 0.5 nm to about 120nm, about 0.5 nm to about 100 nm, about 0.5 nm to about 80 nm, about 0.5nm to about 50 nm, about 0.5 nm to about 40 nm, about 0.5 nm to about 30nm, about 0.5 nm to about 20 nm, about 0.5 nm to about 10 nm, about 0.5nm to about 5 nm, about 0.5 nm to about 1 nm, about 2 nm to about 150nm, about 2 nm to about 120 nm, about 2 nm to about 100 nm, about 2 nmto about 80 nm, about 2 nm to about 50 nm, about 2 nm to about 40 nm,about 2 nm to about 30 nm, about 2 nm to about 20 nm, about 2 nm toabout 10 nm, about 2 nm to about 5 nm, about 2 nm to about 3 nm, about10 nm to about 150 nm, about 10 nm to about 120 nm, about 10 nm to about100 nm, about 10 nm to about 80 nm, about 10 nm to about 50 nm, about 10nm to about 40 nm, about 10 nm to about 30 nm, about 10 nm to about 20nm, or about 10 nm to about 15 nm.

In some examples, such as FIG. 4A, the first deposited layer 410A is achromium-containing layer that contains chromium oxide, chromiumnitride, or a combination thereof, and the second deposited layer 410Acontains one or more of aluminum oxide, silicon nitride, hafnium oxide,hafnium silicate, titanium oxide, or any combination thereof.

The second deposited layer 410A, 516, 616 may be deposited using a CVDprocess. The CVD process may be performed at a temperature of about 300°C. to about 1200° C. The CVD process may be performed at a highertemperature than the ALD process. For example, the ALD process may beperformed at a temperature of about 500° C. and the CVD process may beperformed at a temperature of about 1100° C. The CVD process may be aPECVD process performed at a temperature of about 300° C. to about 1100°C., a low pressure CVD process performed at a temperature of about 500°C. to about 1100° C., or a thermal CVD process performed at atemperature of about 500° C. to about 1100° C. Depositing the seconddeposited layer 410A, 516, 616 by a CVD process may convert the seconddeposited layer 410A, 516, 616 to a crystalline phase. As such, theprotective coating 200, 300, 400, 500, 600 may not need to undergo theannealing and oxidation process. However, the second deposited layer410A, 516, 616 deposited through a CVD process may need to undergo theannealing and oxidation process to convert the second deposited layer410A, 516, 616 to the preferred crystalline assembly.

At block 140, the aerospace component 602 is optionally exposed to athird precursor and a third reactant to form the third deposited layer618 on the second deposited layer 616 to add to the protective coating600, such as shown in FIG. 6A. The first deposited layer 624, the seconddeposited layer 616, and the third deposited layer 618 each havedifferent compositions from each other. In some examples, the thirdprecursor is a different precursor than the first and second precursors.The third deposited layer 618 may have the same thickness as the seconddeposited layer 616. Additionally, the third deposited layer 618 may beformed in the same process or manner as the second deposited layer 616,including deposition method, time, and cycles. As such, all parametersdiscussed at block 130 apply to block 140.

In one or more embodiments, the third precursor is or includes one ormore aluminum precursors; however, the third precursor can be or includeone or more aluminum precursors, one or more chromium precursors, one ormore hafnium precursors, one or more yttrium precursors, or anycombination thereof. In some examples, such as FIG. 6A, the firstdeposited layer 624 is a hafnium doped aluminum oxide, the seconddeposited layer 616 is a chromium-containing layer that containschromium oxide, and the third deposited layer 618 is analuminum-containing layer that contains one or more of aluminum oxide.

At block 150, the method 100 includes optionally repeating exposing theaerospace component 502, 602 to the first precursor and the firstreactant, the second precursor and the second reactant, and/or the thirdprecursor and the third reactant one or more times until a desiredthickness is reached or achieved, such as shown in FIGS. 5A and 6A. Ifthe desired thickness of the protective coating 200, 300, 400 has beenachieved, then move to block 160. If the desired thickness of theprotective coating 500, 600 has not been achieved, then start anotherdeposition cycle of exposing the aerospace component 502 to the firstprecursor and the first reactant to form a third deposited layer 518,exposing the aerospace component 502 to the second precursor and thesecond reactant to form a fourth deposited layer 520, and exposing theaerospace component 502 to the first precursor and the first reactant toform a fifth deposited layer 522 like shown in FIG. 5A, or by exposingthe aerospace component 602 to the second precursor and the secondreactant to form a fourth deposited layer 620 and exposing the aerospacecomponent 602 to the third precursor and the third reactant to form afifth deposited layer 622, like shown in FIG. 6A. The deposition cycleis repeated until achieving the desired thickness of the protectivecoating 500, 600.

In one or more embodiments, the protective coating 500, 600 can containfrom 1, 2, 3, 4, 5, 6, 7, 8, or 9 pairs of the first and seconddeposited layers (e.g., 504A and 516, 518 and 520) or the second andthird deposited layers (e.g., 616 and 618, 620 and 622) to about 10,about 12, about 15, about 20, about 25, about 30, about 40, about 50,about 65, about 80, about 100, about 120, about 150, about 200, about250, about 300, about 500, about 800, or about 1,000 pairs of the firstand second deposited layers 504A, 516 or the second and third depositedlayers 616, 618. For example, the protective coating 500, 600 cancontain from 1 to about 1,000, 1 to about 800, 1 to about 500, 1 toabout 300, 1 to about 250, 1 to about 200, 1 to about 150, 1 to about120, 1 to about 100, 1 to about 80, 1 to about 65, 1 to about 50, 1 toabout 30, 1 to about 20, 1 to about 15, 1 to about 10, 1 to about 8, 1to about 6, 1 to 5, 1 to 4, 1 to 3, about 5 to about 150, about 5 toabout 120, about 5 to about 100, about 5 to about 80, about 5 to about65, about 5 to about 50, about 5 to about 30, about 5 to about 20, about5 to about 15, about 5 to about 10, about 5 to about 8, about 5 to about7, about 10 to about 150, about 10 to about 120, about 10 to about 100,about 10 to about 80, about 10 to about 65, about 10 to about 50, about10 to about 30, about 10 to about 20, about 10 to about 15, or about 10to about 12 pairs of the first and second deposited layers 504A, 516 orthe second and third deposited layers 616, 618. In one or moreembodiments, the protective coating 500, 600 can contain an odd numberof layers such that there is an additional first deposited layer, seconddeposited layer, or third deposited layer, like shown in FIG. 5A.

The protective coating 200, 300, 400, 500, 600 can have a totalthickness of about 1 nm, about 2 nm, about 3 nm, about 5 nm, about 8 nm,about 10 nm, about 12 nm, about 15 nm, about 20 nm, about 30 nm, about50 nm, about 60 nm, about 80 nm, about 100 nm, or about 120 nm to about150 nm, about 180 nm, about 200 nm, about 250 nm, about 300 nm, about350 nm, about 400 nm, about 500 nm, about 800 nm, about 1,000 nm, about2,000 nm, about 3,000 nm, about 4,000 nm, about 5,000 nm, about 6,000nm, about 7,000 nm, about 8,000 nm, about 9,000 nm, about 10,000 nm, orthicker. In some examples, the protective coating 200, 300, 400, 500,600 can have a thickness of less than 10 μm (less than 10,000 nm). Forexample, the protective coating 200, 300, 400, 500, 600 can have athickness of about 1 nm to less than 10,000 nm, about 1 nm to about8,000 nm, about 1 nm to about 6,000 nm, about 1 nm to about 5,000 nm,about 1 nm to about 3,000 nm, about 1 nm to about 2,000 nm, about 1 nmto about 1,500 nm, about 1 nm to about 1,000 nm, about 1 nm to about 500nm, about 1 nm to about 400 nm, about 1 nm to about 300 nm, about 1 nmto about 250 nm, about 1 nm to about 200 nm, about 1 nm to about 150 nm,about 1 nm to about 100 nm, about 1 nm to about 80 nm, about 1 nm toabout 50 nm, about 20 nm to about 500 nm, about 20 nm to about 400 nm,about 20 nm to about 300 nm, about 20 nm to about 250 nm, about 20 nm toabout 200 nm, about 20 nm to about 150 nm, about 20 nm to about 100 nm,about 20 nm to about 80 nm, about 20 nm to about 50 nm, about 30 nm toabout 400 nm, about 30 nm to about 200 nm, about 50 nm to about 500 nm,about 50 nm to about 400 nm, about 50 nm to about 300 nm, about 50 nm toabout 250 nm, about 50 nm to about 200 nm, about 50 nm to about 150 nm,about 50 nm to about 100 nm, about 80 nm to about 250 nm, about 80 nm toabout 200 nm, about 80 nm to about 150 nm, about 80 nm to about 100 nm,about 50 nm to about 80 nm, about 100 nm to about 500 nm, about 100 nmto about 400 nm, about 100 nm to about 300 nm, about 100 nm to about 250nm, about 100 nm to about 200 nm, or about 100 nm to about 150 nm.

At block 160, an optional oxidation and annealing process is performedon the protective coating 200, 300, 400, 500, 600, as shown in FIGS. 2B,3B, 4B, 5B, and 6B. For example, the optional annealing and oxidationprocess may be performed when one or more of the deposited layers aredeposited in the amorphous phase. Additionally, if one or more layersare deposited by a CVD process, the CVD process may convert the one ormore layers to a crystalline phase. As such, the protective coating 200,300, 400, 500, 600 may not need to undergo the annealing and oxidationprocess. However, the one or more layers deposited through a CVD processmay need to undergo the annealing and oxidation process to convert theone or more layers to the preferred crystalline assembly. The annealingand oxidation process may be performed at a temperature of about 500° C.to about 1,100° C.

The oxidizing process may partially oxidize the protective coating 200,300, 400, 500, 600. In some examples, the protective coating 200, 300,400, 500, 600 can be converted into the coalesced layer 208, 308, 408,508, 608 during the oxidation and annealing process. During theoxidation and annealing process, the high temperature coalesces thelayers within the protective coating 200, 300, 400, 500, 600 into asingle structure where the new crystalline assembly enhances theintegrity and protective properties of the protective coating 200 or thecoalesced layer 208, 308, 408, 508, 608.

The protective coating 200, 300, 400, 500, 600 having a crystallineassembly enhances the strength, longevity, and durability of theprotective coating 200, 300, 400, 500, 600, and reduces both theoxidation rate of the surface of the aerospace component 202, 302, 402,502, 602 and the rate of depletion of aluminum from the aerospacecomponent 202, 302, 402, 502, 602. As such, the protective coating 200,300, 400, 500, 600 being in a crystalline phase increases the oxidationand corrosion resistance of the aerospace component 202, 302, 402, 502,602. The annealing process can be or include a thermal anneal, a plasmaanneal, an ultraviolet anneal, a laser anneal, or any combinationthereof. Additionally, each deposited layer of the protective coating200, 300, 400, 500, 600 may be annealed and oxidized individually priorto depositing another layer, rather than annealing and oxidizing alldeposited layers together at the same time. Performing the optionalannealing and oxidizing process may further enhance and strengthen theprotective properties of the protective coating 200, 300, 400, 500, 600.

Furthermore, during the oxidation and annealing process, a layer orregion 206, 306, 406, 506, 606 of the aerospace component 202, 302, 402,502, 602 nearest the protective coating 200, 300, 400, 500, 600 isdepleted of aluminum or an aluminum-rich phase, forming the intermediateregion 206, 306, 406, 506, 606 disposed between the aerospace component202, 302, 402, 502, 602 and the first deposited layer 204, 310A, 404A,504A, 624, and further forming an aluminum oxide layer or region 204,314, 404B, 504B, 624 in the coalesced layer 208, 308, 408, 508, 608.Aluminum from the intermediate region 206, 306, 406, 506, 606 diffusesinto the coalesced layer 208, 308, 408, 508, 608, depleting theintermediate region 206, 306, 406, 506, 606 of aluminum andsimultaneously forming the aluminum oxide layer or region 204, 314,404B, 504B, 624. The aluminum oxide layer or region 204, 314, 404B,504B, 624 is formed having a crystalline assembly.

The thickness of the intermediate region 206, 306, 406, 506, 606 mayvary due to several factors, such as the amount of aluminum present inthe aerospace component 202, 302, 402, 502, 602, the amount of time theprotective coating 200, 300, 400, 500, 600 is annealed, and thetemperature of the annealing process. However, the protective coating200, 300, 400, 500, 600 having the preferred crystalline assemblydecreases the rate of depletion of aluminum from the intermediate region206, 306, 406, 506, 606, and further protects the aerospace component202, 302, 402, 502, 602 from corrosion and oxidation.

The crystalline protective coatings 200, 300, 400, 500, 600 reduces theamount of nickel containing oxides formed at the surface of theaerospace component 202, 302, 402, 502, 602. For example, utilizing theprotective coatings 200, 300, 400, 500, 600 results in less than 10% ofnickel containing oxides from forming on the surface of the aerospacecomponent 202, 302, 402, 502, 602, such as less than 5%.

During the oxidation and annealing process, the protective coating 200,300, 400, 500, 600 disposed on the aerospace component 202, 302, 402,502, 602 is heated to a temperature of greater than about 500° C. Insome embodiments, the protective coating 200, 300, 400, 500, 600disposed on the aerospace component 202, 302, 402, 502, 602 is heated toa temperature of greater than about 800° C. For example, the protectivecoating 200, 300, 400, 500, 600 disposed on the aerospace component 202,302, 402, 502, 602 is heated to a temperature of about 500° C. to about1,500° C., about 600° C. to about 1,400° C., about 700° C. to about1,300° C., about 800° C. to about 1,200° C., about 900° C. to about1,100° C., about 900° C. to about 1,000° C., or about 1050° C. duringthe oxidation and annealing process. The oxidation and annealing processmay occur in an environment of air. If more than one annealing andoxidation process is performed (i.e., annealing and oxidizing depositedlayers individually), each annealing and oxidizing process may occur atthe same temperature, or each annealing and oxidizing process may occurat different temperatures.

The protective coating 200, 300, 400, 500, 600 can be under a vacuum ata low pressure (e.g., from about 0.1 Torr to less than 760 Torr), atambient pressure (e.g., about 760 Torr), and/or at a high pressure(e.g., from greater than 760 Torr (1 atm) to about 3,678 Torr (about 5atm)) during the oxidation and annealing process. The protective coating200, 300, 400, 500, 600 can be exposed to an atmosphere containing oneor more gases during the oxidation and annealing process. Exemplarygases used during the annealing process can be or include nitrogen (N₂),argon, helium, hydrogen (H₂), oxygen (O₂), air, or any combinationsthereof. The oxidation and annealing process can be performed for about0.01 seconds to about 10 minutes. In some examples, the oxidation andannealing process can be a thermal anneal and lasts for about 1 minuteto about 24 hours, such as about 10 minutes to about 10 hours. In otherexamples, the oxidation and annealing process can be a laser anneal or aspike anneal and lasts for about 1 millisecond, about 100 millisecond,or about 1 second to about 5 seconds, about 10 seconds, or about 15seconds.

The protective coating 200, 300, 400, 500, 600 can have a thickness ofabout 1 nm, about 2 nm, about 3 nm, about 5 nm, about 8 nm, about 10 nm,about 12 nm, about 15 nm, about 20 nm, about 30 nm, about 50 nm, about60 nm, about 80 nm, about 100 nm, or about 120 nm to about 150 nm, about180 nm, about 200 nm, about 250 nm, about 300 nm, about 350 nm, about400 nm, about 500 nm, about 700 nm, about 850 nm, about 1,000 nm, about1,200 nm, about 1,500 nm, about 2,000 nm, about 3,000 nm, about 4,000nm, about 5,000 nm, about 6,000 nm, about 7,000 nm, about 8,000 nm,about 9,000 nm, about 10,000 nm, or thicker. In some examples, theprotective coating 250 or the coalesced film 240 can have a thickness ofless than 10 μm (less than 10,000 nm). For example, protective coating200, 300, 400, 500, 600 can have a thickness of about 1 nm to less than10,000 nm, about 1 nm to about 8,000 nm, about 1 nm to about 6,000 nm,about 1 nm to about 5,000 nm, about 1 nm to about 3,000 nm, about 1 nmto about 2,000 nm, about 1 nm to about 1,500 nm, about 1 nm to about1,000 nm, about 1 nm to about 500 nm, about 1 nm to about 400 nm, about1 nm to about 300 nm, about 1 nm to about 250 nm, about 1 nm to about200 nm, about 1 nm to about 150 nm, about 1 nm to about 100 nm, about 1nm to about 80 nm, about 1 nm to about 50 nm, about 20 nm to about 500nm, about 20 nm to about 400 nm, about 20 nm to about 300 nm, about 20nm to about 250 nm, about 20 nm to about 200 nm, about 20 nm to about150 nm, about 20 nm to about 100 nm, about 20 nm to about 80 nm, about20 nm to about 50 nm, about 30 nm to about 400 nm, about 30 nm to about200 nm, about 50 nm to about 500 nm, about 50 nm to about 400 nm, about50 nm to about 300 nm, about 50 nm to about 250 nm, about 50 nm to about200 nm, about 50 nm to about 150 nm, about 50 nm to about 100 nm, about80 nm to about 250 nm, about 80 nm to about 200 nm, about 80 nm to about150 nm, about 80 nm to about 100 nm, about 50 nm to about 80 nm, about100 nm to about 500 nm, about 100 nm to about 400 nm, about 100 nm toabout 300 nm, about 100 nm to about 250 nm, about 100 nm to about 200nm, or about 100 nm to about 150 nm.

In one or more embodiments, the protective coating 200, 300, 400, 500,600 can have a relatively high degree of uniformity. The protectivecoating 200, 300, 400, 500, 600 can have a uniformity of less than 50%,less than 40%, or less than 30% of the thickness of the respectiveprotective coating 200, 250. The protective coating 200, 300, 400, 500,600 can independently have a uniformity from about 0%, about 0.5%, about1%, about 2%, about 3%, about 5%, about 8%, or about 10% to about 12%,about 15%, about 18%, about 20%, about 22%, about 25%, about 28%, about30%, about 35%, about 40%, about 45%, or less than 50% of the thickness.For example, the protective coating 200, 300, 400, 500, 600 canindependently have a uniformity from about 0% to about 50%, about 0% toabout 40%, about 0% to about 30%, about 0% to less than 30%, about 0% toabout 28%, about 0% to about 25%, about 0% to about 20%, about 0% toabout 15%, about 0% to about 10%, about 0% to about 8%, about 0% toabout 5%, about 0% to about 3%, about 0% to about 2%, about 0% to about1%, about 1% to about 50%, about 1% to about 40%, about 1% to about 30%,about 1% to less than 30%, about 1% to about 28%, about 1% to about 25%,about 1% to about 20%, about 1% to about 15%, about 1% to about 10%,about 1% to about 8%, about 1% to about 5%, about 1% to about 3%, about1% to about 2%, about 5% to about 50%, about 5% to about 40%, about 5%to about 30%, about 5% to less than 30%, about 5% to about 28%, about 5%to about 25%, about 5% to about 20%, about 5% to about 15%, about 5% toabout 10%, about 5% to about 8%, about 10% to about 50%, about 10% toabout 40%, about 10% to about 30%, about 10% to less than 30%, about 10%to about 28%, about 10% to about 25%, about 10% to about 20%, about 10%to about 15%, or about 10% to about 12% of the thickness.

In some embodiments, the protective coating 200, 300, 400, 500, 600contain can be formed or otherwise produced with different ratios ofmetals throughout the material, such as a doping metal or grading metalcontained within a base metal, where any of the metal can be in anychemically oxidized form (e.g., oxide, nitride, silicide, carbide, orcombinations thereof). In one or more examples, the first depositedlayer 204, 310A, 404A, 504A, 624 is deposited to first thickness and thesecond deposited layer 410A, 516, 616 is deposited to a secondthickness, where the first thickness or less than or greater than thesecond thickness. For example, the first deposited layer 204, 310A,404A, 504A, 624 can be deposited by two or more (3, 4, 5, 6, 7, 8, 9,10, or more) ALD cycles during block 120 to produce the respectivelysame amount of sub-layers (e.g., one sub-layer for each ALD cycle), andthen the second deposited layer 410A, 516, 616 can be deposited by oneALD cycle or a number of ALD cycles that is less than or greater thanthe number of ALD cycles used to deposit the first deposited layer 204,310A, 404A, 504A, or 624. In other examples, the first deposited layer204, 310A, 404A, 504A, 624 can be deposited by CVD to a first thicknessand the second deposited layer 410A, 516, 616 is deposited by ALD to asecond thickness which is less than the first thickness.

In other embodiments, an ALD process can be used to deposit the firstdeposited layer 204, 310A, 404A, 504A, 624 and/or the second depositedlayer 410A, 516, 616 where the deposited material is doped by includinga dopant precursor during the ALD process. In some examples, the dopantprecursor can be included in a separate ALD cycle relative to the ALDcycles used to deposit the base material. In other examples, the dopantprecursor can be co-injected with any of the chemical precursors usedduring the ALD cycle. In further examples, the dopant precursor can beinjected separate from the chemical precursors during the ALD cycle. Forexample, one ALD cycle can include exposing the aerospace component to:the first precursor, a pump-purge, the dopant precursor, a pump-purge,the first reactant, and a pump-purge to form the deposited layer. Insome examples, one ALD cycle can include exposing the aerospacecomponent to: the dopant precursor, a pump-purge, the first precursor, apump-purge, the first reactant, and a pump-purge to form the depositedlayer. In other examples, one ALD cycle can include exposing theaerospace component to: the first precursor, the dopant precursor, apump-purge, the first reactant, and a pump-purge to form the depositedlayer.

In one or more embodiments, the first deposited layer 204, 310A, 404A,504A, 624 and/or the second deposited layer 410A, 516, 616 contains oneor more base materials and one or more doping materials. The basematerial is or contains aluminum oxide, chromium oxide, or a combinationof aluminum oxide and chromium oxide. The doping material is or containshafnium, hafnium oxide, yttrium, yttrium oxide, cerium, cerium oxide,silicon, silicon oxide, nitrides thereof, or any combination thereof.Any of the precursors or reagents described herein can be used as adoping precursor or a dopant. Exemplary cerium precursor can be orinclude one or more cerium(IV)tetra(2,2,6,6-tetramethyl-3,5-heptanedionate) (Ce(TMHD)₄),tris(cyclopentadiene) cerium ((C₅H₅)₃Ce), tris(propylcyclopentadiene)cerium ([(C₃H₇)C₅H₄]₃Ce), tris(tetramethylcyclopentadiene) cerium([(CH₃)₄C₅H]₃Ce), or any combination thereof.

The doping material can have a concentration of about 0.01 atomicpercent (at %), about 0.05 at %, about 0.08 at %, about 0.1 at %, about0.5 at %, about 0.8 at %, about 1 at %, about 1.2 at %, about 1.5 at %,about 1.8 at %, or about 2 at % to about 2.5 at %, about 3 at %, about3.5 at %, about 4 at %, about 5 at %, about 8 at %, about 10 at %, about15 at %, about 20 at %, about 25 at %, or about 30 at % within the firstdeposited layer 204, 310A, 404A, 504A, or 624, the second depositedlayer 410A, 516, 616, the protective coating 200, 300, 400, 500, 600,and/or the coalesced layer 208, 308, 408, 508, 608. For example, thedoping material can have a concentration of about 0.01 at % to about 30at %, about 0.01 at % to about 25 at %, about 0.01 at % to about 20 at%, about 0.01 at % to about 15 at %, about 0.01 at % to about 12 at %,about 0.01 at % to about 10 at %, about 0.01 at % to about 8 at %, about0.01 at % to about 5 at %, about 0.01 at % to about 4 at %, about 0.01at % to about 3 at %, about 0.01 at % to about 2.5 at %, about 0.01 at %to about 2 at %, about 0.01 at % to about 1.5 at %, about 0.01 at % toabout 1 at %, about 0.01 at % to about 0.5 at %, about 0.01 at % toabout 0.1 at %, about 0.1 at % to about 30 at %, about 0.1 at % to about25 at %, about 0.1 at % to about 20 at %, about 0.1 at % to about 15 at%, about 0.1 at % to about 12 at %, about 0.1 at % to about 10 at %,about 0.1 at % to about 8 at %, about 0.1 at % to about 5 at %, about0.1 at % to about 4 at %, about 0.1 at % to about 3 at %, about 0.1 at %to about 2.5 at %, about 0.1 at % to about 2 at %, about 0.1 at % toabout 1.5 at %, about 0.1 at % to about 1 at %, about 0.1 at % to about0.5 at %, about 1 at % to about 30 at %, about 1 at % to about 25 at %,about 1 at % to about 20 at %, about 1 at % to about 15 at %, about 1 at% to about 12 at %, about 1 at % to about 10 at %, about 1 at % to about8 at %, about 1 at % to about 5 at %, about 1 at % to about 4 at %,about 1 at % to about 3 at %, about 1 at % to about 2.5 at %, about 1 at% to about 2 at %, or about 1 at % to about 1.5 at % within the firstdeposited layer 204, 310A, 404A, 504A, or 624, the second depositedlayer 410A, 516, 616, the protective coating 200, 300, 400, 500, 600,and/or the coalesced layer 208, 308, 408, 508, 608.

In one or more embodiments, the protective coating 200, 300, 400, 500,600 includes the first deposited layer 204, 310A, 404A, 504A, 624containing aluminum oxide (or other base material) and the seconddeposited layer 410A, 516, 616 containing chromium oxide (or otherdoping material), or having the first deposited layer 204, 310A, 404A,504A, 624 containing chromium oxide (or other doping material) and thesecond deposited layer 410A, 516, 616 containing aluminum oxide (orother base material). In one or more examples, the protective coatings200, 300, 400, 500, 600 contain a combination of aluminum oxide andchromium oxide, a hafnium-doped aluminum oxide, hafnium aluminate, orany combination thereof. For example, the first deposited layer 204,310A, 404A, 504A, 624 contains aluminum oxide and the second depositedlayer 410A, 516, 616 contains chromium oxide, or having the firstdeposited layer 204, 310A, 404A, 504A, 624 contains chromium oxide andthe second deposited layer 410A, 516, 616 contains aluminum oxide. Inother examples, the protective coating 300, 400, 500, 600 includes thecoalesced layer 208, 308, 408, 508, 608 formed from layers of aluminumoxide and chromium oxide. In one or more embodiments, the protectivecoating 200, 300, 400, 500, 600 has a concentration of hafnium (or otherdoping material) of about 0.01 at %, about 0.05 at %, about 0.08 at %,about 0.1 at %, about 0.5 at %, about 0.8 at %, or about 1 at % to about1.2 at %, about 1.5 at %, about 1.8 at %, about 2 at %, about 2.5 at %,about 3 at %, about 3.5 at %, about 4 at %, about 4.5 at %, or about 5at % within the coalesced layer 208, 308, 408, 508, 608 containingaluminum oxide (or other base material). For example, the protectivecoating 600 has a concentration of hafnium (or other doping material) ofabout 0.01 at % to about 10 at %, about 0.01 at % to about 8 at %, about0.01 at % to about 5 at %, about 0.01 at % to about 4 at %, about 0.01at % to about 3 at %, about 0.01 at % to about 2.5 at %, about 0.01 at %to about 2 at %, about 0.01 at % to about 1.5 at %, about 0.01 at % toabout 1 at %, about 0.01 at % to about 0.5 at %, about 0.01 at % toabout 0.1 at %, about 0.01 at % to about 0.05 at %, about 0.1 at % toabout 5 at %, about 0.1 at % to about 4 at %, about 0.1 at % to about 3at %, about 0.1 at % to about 2.5 at %, about 0.1 at % to about 2 at %,about 0.1 at % to about 1.5 at %, about 0.1 at % to about 1 at %, about0.1 at % to about 0.5 at %, about 0.5 at % to about 5 at %, about 0.5 at% to about 4 at %, about 0.5 at % to about 3 at %, about 0.5 at % toabout 2.5 at %, about 0.5 at % to about 2 at %, about 0.5 at % to about1.5 at %, about 0.5 at % to about 1 at %, about 1 at % to about 5 at %,about 1 at % to about 4 at %, about 1 at % to about 3 at %, about 1 at %to about 2.5 at %, about 1 at % to about 2 at %, or about 1 at % toabout 1.5 at % within the coalesced layer 608 containing aluminum oxide(or other base material).

FIGS. 7A and 7B are schematic views of an aerospace component 700comprising nickel and aluminum having a protective coating 730 disposedthereon, according to one or more embodiments described and discussedherein. FIG. 7A is a perspective view of the aerospace component 700 andFIG. 7B is a cross-sectional view of the aerospace component 700. Theprotective coating 730 can be or include one or more deposited layers,one or more coalesced films, or any combination thereof, as describedand discussed herein. For example, the protective coating 730 can be orinclude one or more of the protective coating 200 of FIG. 2B, theprotective coating 300 of FIG. 3B, the protective coating 400 of FIG.4B, the protective coating 500 of FIG. 5B, and/or the protective coating600 of FIG. 6B. Similarly, the aerospace component 700 can be or includethe aerospace component 202, 302, 402, 502, 602 of FIGS. 2A-2B, FIGS.3A-3B, FIGS. 4A-4B, FIGS. 5A-5B, and FIGS. 6A-6B, respectively.Aerospace components as described and discussed herein, includingaerospace component 700, can be or include one or more components orportions thereof of a turbine, an aircraft, a spacecraft, or otherdevices that can include one or more turbines (e.g., compressors, pumps,turbo fans, super chargers, and the like). Exemplary aerospacecomponents 700 can be or include a turbine blade, a turbine vane, asupport member, a frame, a rib, a fin, a pin fin, a combustor fuelnozzle, a combustor shield, an internal cooling channel, or anycombination thereof.

The aerospace component 700 has one or more outer or exterior surfaces710 and one or more inner or interior surfaces 720. The interiorsurfaces 720 can define one or more cavities 702 extending or containedwithin the aerospace component 700. The cavities 702 can be channels,passages, spaces, or the like disposed between the interior surfaces720. The cavity 702 can have one or more openings 704, 706, and 708.Each of the cavities 702 within the aerospace component 700 typicallyhave aspect ratios (e.g., length divided by width) of greater than 1.The methods described and discussed herein provide depositing and/orotherwise forming the protective coatings 200, 300, 400, 500, 600 on theinterior surfaces 720 with high aspect ratios (greater than 1) and/orwithin the cavities 702.

The aspect ratio of the cavity 702 can be from about 2, about 3, about5, about 8, about 10, or about 12 to about 15, about 20, about 25, about30, about 40, about 50, about 65, about 80, about 100, about 120, about150, about 200, about 250, about 300, about 500, about 800, about 1,000,or greater. For example, the aspect ratio of the cavity 702 can be fromabout 2 to about 1,000, about 2 to about 500, about 2 to about 200,about 2 to about 150, about 2 to about 120, about 2 to about 100, about2 to about 80, about 2 to about 50, about 2 to about 40, about 2 toabout 30, about 2 to about 20, about 2 to about 10, about 2 to about 8,about 5 to about 1,000, about 5 to about 500, about 5 to about 200,about 5 to about 150, about 5 to about 120, about 5 to about 100, about5 to about 80, about 5 to about 50, about 5 to about 40, about 5 toabout 30, about 5 to about 20, about 5 to about 10, about 5 to about 8,about 10 to about 1,000, about 10 to about 500, about 10 to about 200,about 10 to about 150, about 10 to about 120, about 10 to about 100,about 10 to about 80, about 10 to about 50, about 10 to about 40, about10 to about 30, about 10 to about 20, about 20 to about 1,000, about 20to about 500, about 20 to about 200, about 20 to about 150, about 20 toabout 120, about 20 to about 100, about 20 to about 80, about 20 toabout 50, about 20 to about 40, or about 20 to about 30.

The aerospace component 700 and any surface thereof including one ormore outer or exterior surfaces 710 and/or one or more inner or interiorsurfaces 720 can be made of, contain, or otherwise include one or moremetals, such as nickel, aluminum, chromium, iron, titanium, hafnium, oneor more nickel superalloys, one or more Inconel alloys, one or moreHastelloy alloys, one or more Monel alloys, alloys thereof, or anycombination thereof. For example, the aerospace component 700 maycomprise Inconel 617, Inconel 625, Inconel 718, Inconel X-750, Haynes214 alloy, Monel 404, and/or Monel K-500. The protective coating 730 canbe deposited, formed, or otherwise produced on any surface of theaerospace component 700 including one or more outer or exterior surfaces710 and/or one or more inner or interior surfaces 720.

The protective coating, as described and discussed herein, can be orinclude one or more of laminate film stacks, coalesced films, gradedcompositions, and/or monolithic films which are deposited or otherwiseformed on any surface of an aerospace component. In some examples, theprotective coating contains from about 1% to about 100% chromium oxide.The protective coatings are conformal and substantially coat roughsurface features following surface topology, including in open pores,blind holes, and non-line-of sight regions of a surface. The protectivecoatings do not substantially increase surface roughness, and in someembodiments, the protective coatings may reduce surface roughness byconformally coating roughness until it coalesces. The protectivecoatings may contain particles from the deposition that aresubstantially larger than the roughness of the aerospace component, butare considered separate from the monolithic film. The protectivecoatings are substantially well adhered and pinhole free. The thicknessof the protective coatings varies within 1-sigma of 40%. In one or moreembodiments, the thickness varies less than 1-sigma of 20%, 10%, 5%, 1%,or 0.1%.

The protective coatings provide corrosion and oxidation protection whenthe aerospace components are exposed to air, oxygen, sulfur and/orsulfur compounds, acids, bases, salts (e.g., Na, K, Mg, Li, or Casalts), or any combination thereof.

One or more embodiments described herein include methods for thepreservation of an underneath chromium-containing alloy using themethods producing an alternating nanolaminate of first material (e.g.,chromium oxide, aluminum oxide, and/or aluminum nitride) and anothersecondary material. The secondary material can be or include one or moreof aluminum oxide, aluminum nitride, aluminum oxynitride, silicon oxide,silicon nitride, silicon carbide, yttrium oxide, yttrium nitride,yttrium silicon nitride, hafnium oxide, hafnium silicate, hafniumsilicide, hafnium nitride, titanium oxide, titanium nitride, titaniumsilicide, titanium silicate, dopants thereof, alloys thereof, or anycombination thereof. The resultant film can be used as a nanolaminatefilm stack or the film can be subjected to annealing where the hightemperature coalesces the films into a single structure where the newcrystalline assembly enhances the integrity and protective properties ofthis overlying film.

In a particular embodiment, the chromium precursor (at a temperature ofabout 0° C. to about 250° C.) is delivered to the aerospace componentvia vapor phase delivery for at pre-determined pulse length of 5seconds. During this process, the deposition reactor is operated under aflow of nitrogen carrier gas (about 1,000 sccm total) with the chamberheld at a pre-determined temperature of about 350° C. and pressure ofabout 3.5 Torr. After the pulse of the chromium precursor, the chamberis then subsequently pumped and purged of all requisite gases andbyproducts for a determined amount of time. Subsequently, water ispulsed into the chamber for 0.1 seconds at chamber pressure of about 3.5Torr. An additional chamber purge (or pump/purge) is then performed torid the reactor of any excess reactants and reaction byproducts. Thisprocess is repeated as many times as necessary to get the target CrOxfilm to the desired film thickness.

For the secondary film (example: aluminum oxide), the precursor,trimethylaluminum (at a temperature of about 0° C. to about 30° C.) isdelivered to the aerospace component via vapor phase delivery for atpre-determined pulse length of 0.1 seconds. During this process, thedeposition reactor is operated under a flow of nitrogen carrier gas (100sccm total) with the chamber held at a pre-determined temperature ofabout 150° C. to about 350° C. and pressure about 1 Torr to about 5Torr. After the pulse of trimethylaluminum, the chamber is thensubsequently pumped and purged of all requisite gases and byproducts fora determined amount of time. Subsequently, water vapor is pulsed intothe chamber for about 0.1 seconds at chamber pressure of about 3.5 Torr.An additional chamber purge is then performed to rid the reactor of anyexcess reactants and reaction byproducts. This process is repeated asmany times as necessary to get the target Al₂O₃ film to the desired filmthickness. The aerospace component is then subjected to an annealingfurnace at a temperature of about 500° C. under inert nitrogen flow ofabout 500 sccm for about one hour.

Doped/alloyed ALD Layers Processes

One or more embodiments described herein include methods for thepreservation of an underlying aerospace component by using a dopedchromium-containing film or a doped aluminum containing film. This filmis or includes a chromium-containing film produced by using a chromiumprecursor or an aluminum precursos, and one or more of oxygen sources oroxidizing agents (for chromium oxide or aluminum oxide deposition),nitrogen sources or nitriding agents (for chromium nitride or aluminumnitride deposition), one or more carbon sources or carbon precursors(for chromium carbide or aluminum carbide deposition), silicon sourcesor silicon precursors (for chromium silicide or aluminum silicidedeposition), or any combination thereof. A doping precursor (or dopant)can be or include a source for aluminum, yttrium, hafnium, silicon,tantalum, zirconium, strontium, lanthanum, neodymium, holmium, barium,lutetium, dysprosium, samarium, terbium, erbium, thulium, titanium,niobium, manganese, scandium, europium, tin, cerium, or any combinationthereof. The precursors used can be or include, but is not limited to,one or more chromium precursors or one or more aluminum precursors, asdescribed and discussed above. The chromium precursor can be used duringa deposition process to produce doped film containing the ternarymaterial (e.g., YCrO or CrAlO). The resultant film can be used as ananolaminate film stack or the film can be subjected to annealing wherethe high temperature coalesces the films into a single structure wherethe new crystalline assembly enhances the integrity and protectiveproperties of this overlying film.

In a particular embodiment, the chromium precursor,bis(1,4-ditertbutyldiazadienyl chromium (II) (at a temperature of about0° C. to about 250° C.) is delivered to the aerospace component viavapor phase delivery for at pre-determined pulse length of 5 seconds.During this process, the deposition reactor is operated under a flow ofnitrogen carrier gas of about 1,000 sccm with the chamber held at apre-determined temperature of about 350° C. and pressure of about 3.5Torr. After the pulse of the chromium precursor, the chamber is thensubsequently pumped and purged of all requisite gases and byproducts fora determined amount of time. Subsequently, a second reactant, water ispulsed into the chamber for 0.1 seconds at chamber pressure of about 3.5Torr. A second chamber purge is then performed to rid the reactor of anyexcess reactants and reaction byproducts.

This chromium precursor/pump-purge/water/pump-purge sequence is repeatedas many times as necessary to get the target CrOx film to the desiredfilm thickness. This process results in the formation of a first CrOxlaminate layer with desired thickness.

After the first CrOx laminate layer deposition, a third reactant,tetrakis(ethylmethylamino)hafnium (TEMAH) is pulsed into the chamber for5 seconds at chamber pressure of about 1.6 Torr. A final chamberpump/purge is then performed to rid the reactor of any excess reactantsand reaction byproducts. Subsequently, a second reactant, water ispulsed into the chamber for 3 seconds at chamber pressure of about 1.2Torr. A second chamber pump/purge is then performed to rid the reactorof any excess reactants and reaction byproducts. This single sequenceresults in the formation of a second HfOx laminate layer with monolayer(HfOx) thickness.

This first CrOx/second HfOx laminate layer sequence is repeated as manytimes as necessary to get the target Hf-doped chromium oxide film(CrOx:Hf) to the desired film thickness. The resultant CrOx:Hf film canbe used as a nanolaminate film stack or the film can be subjected toannealing where the high temperature activates Hf diffusion into a CrOxlayers where the more uniform Hf distribution in CrOx:Hf film enhancesthe integrity and protective properties of this overlying film.

In a particular embodiment, the selected Al precursor, trimethylaluminum(TMAl) (at a temperature of about 0° C. to about 30° C.) is delivered tothe aerospace component via vapor phase delivery for at pre-determinedpulse length of about 0.1 seconds to about 1 second. During thisprocess, the deposition reactor is operated under a flow of nitrogencarrier gas of about 100 sccm with the chamber held at a pre-determinedtemperature of about 150° C. to about 400° C. and pressure of about 1Torr to about 5 Torr. After the pulse of trimethylaluminum, the chamberis then subsequently pumped and purged of all requisite gases andbyproducts for a determined amount of time. Subsequently, water vapor ispulsed into the chamber for 3 seconds at chamber pressure of about 1Torr to about 5 Torr. An additional chamber purge is then performed torid the reactor of any excess reactants and reaction byproducts. Thealuminum precursor/pump-purge/water/pump-purge sequence is repeated asmany times as necessary to get the target AlOx (e.g., Al₂O₃) film to thedesired film thickness. This process results in the formation of a firstAlOx laminate layer with desired thickness.

After first AlOx laminate layer deposition, a third reactant,tetrakis(ethylmethylamino)hafnium (TEMAH) is pulsed into the chamber forabout 5 seconds at chamber pressure of about 1.6 Torr. A final chamberpump/purge is then performed to rid the reactor of any excess reactantsand reaction byproducts. Subsequently, a second reactant, water ispulsed into the chamber for about 3 seconds at chamber pressure of about1.2 Torr. A second chamber pump/purge is then performed to rid thereactor of any excess reactants and reaction byproducts. This singlesequence results in the formation of a second HfOx laminate layer withmonolayer (HfOx) thickness.

This first AlOx/second HfOx laminate layer sequence is repeated as manytimes as necessary to get the target Hf-doped aluminum oxide film(AlOx:Hf) to the desired film thickness. In some examples, the resultantAlOx:Hf film is used as a nanolaminate film stack. In other examples,the resultant AlOx:Hf film is subjected to annealing where the hightemperature activates Hf diffusion into a AlOx layers where the moreuniform Hf distribution in AlOx:Hf film enhances the integrity andprotective properties of this overlying film.

SEM shows cross-sections of ALD as-grown Hf doped Al₂O₃ layers on Siaerospace component. SEM shows cross-section of Hf doped Al₂O₃ layerwith about 0.1 at % Hf concentration. The total Al₂O₃:Hf film thicknessis about 140 nm. The film contains six Al₂O₃/HfO₂ laminate layers. Thesingle Al₂O₃/HfO₂ laminate layer thickness is about 23 nm. SEM showscross-section of Hf doped Al₂O₃ layer with about 0.5 at % Hfconcentration. The total Al₂O₃:Hf film thickness is about 108 nm. Thefilm contains twenty one Al₂O₃/HfO₂ laminate layers. The singleAl₂O₃/HfO₂ laminate layer thickness is about 5.1 nm.

The visual differentiation of HfO₂ and Al₂O₃ layers on SEM cross sectionis clear seen for about 0.1 at % Hf doped sample. However SEM resolution(10 nm) limits the visual differentiation of HfO₂ and Al₂O₃ layers forabout 0.5 at % Hf doped sample. SIMS is used to determine concentrationdepth profiles of ALD as-grown Hf doped Al₂O₃ layers on the aerospacecomponent. A SIMS concentration depth profile of Hf doped Al₂O₃ layer isabout 0.1 at % Hf concentration. The film contains six Al₂O₃/HfO₂laminate layers. A SIMS concentration depth profile of Hf doped Al₂O₃layer is about 0.5 at % Hf concentration. The film contains of twentyone Al₂O₃/HfO₂ laminate layers.

Rutherford backscattering spectrometry (RBS) provides compositionalanalysis data for ALD as-grown Hf doped Al₂O₃ layers. The RBS analysisproved what bulk Al₂O₃:Hf layer with six Al₂O₃/HfO₂ laminate layers hasabout 0.1 at % Hf concentration, and bulk Al₂O₃:Hf layer with twenty oneAl₂O₃/HfO₂ laminate layers has about 0.5 at % Hf concentration.

In one or more embodiments, the protective coatings which includechromium containing materials are desirable for a number of applicationswhere a stable chromium oxide forms in air to protect the surface fromoxidation, acid attack, and sulfur corrosion. In the instance of Fe, Co,and/or Ni-based alloys, chromium oxides (as well as aluminum oxides) areformed selectively to create a passivated surface. However, prior toforming this selective oxide layer, other metallic elements will oxidizeuntil the chromium oxide forms a continuous layer.

After the formation of a dense chromium oxide layer, exposure to hightemperatures (e.g., greater than 500° C.) in air causes thickening ofthe chromium oxide scale, where chromium diffuses out of the bulk metaland into the scale, and oxygen diffuses from the air into the scale.Over time, the scale growth rate slows as the scale thickens because (1)oxygen diffusion is slower and (2) chromium becomes depleted in the bulkalloy. For alloys, if the chromium concentration falls below athreshold, other oxides may begin to form which cause the spallation orfailure of the previously protective scale.

To extend the life of a chromium-containing alloy, one or more of thefollowing methods can be used. In one or more embodiments, the methodcan include depositing an oxide layer matching the composition andcrystal structure of the native oxide to produce the protective coating.In other embodiments, the method can include depositing an oxide layerwith a different crystal structure to the native oxide to produce theprotective coating. In some embodiments, the method can includedepositing an oxide layer with additional dopants that would not bepresent in the native oxide to produce the protective coating. In otherembodiments, the method can include depositing another oxide (e.g.,silicon oxide or aluminum oxide) as a capping layer or in a multi-layerstack to produce the protective coating.

In one or more embodiments of the method, a non-native oxide may beinitially deposited onto the surface of the metal surface of aerospacecomponent or other substrate that effectively thickens the oxide,thereby slowing oxygen diffusion toward the metal surface and resultingin slower absolute thicknesses growth of the oxide film. In someexamples, a benefit of this approach can be contemplated in the contextof a parabolic oxide scale growth curve. At thicker scales (e.g.,greater than 0.5 micron to about 1.5 micron), the rate of scalethickness decreases versus initial growth. By depositing an oxide filmhaving a thickness of about 100 nm, about 200 nm, or about 300 nm toabout 1 micron, about 2 micron, or about 3 micron prior to the growth ofa thick scale. The effective growth rate of the first thickness of about0.5 micron to about 1 micron of native scale can be much slower over agiven period of time. In turn, the rate of depletion of chromium fromthe substrate can be slower, and the time a surface can be exposed tothe environment can be longer.

Oxygen diffusion can further be slowed by depositing a predeterminedcrystalline structure of chromium oxide, e.g., amorphous. Oxygen candiffuse along grain boundaries faster than in bulk crystals for chromiumoxide, so minimizing grain boundaries can be beneficial for slowingoxygen diffusion. In turn, scale growth can be slower, and the time asurface can be exposed to the environment can be longer.

In other embodiments, the method can include incorporating one or moredopants into the deposited oxide while producing the protective coating.The dopant can be or include a source for aluminum, yttrium, hafnium,silicon, tantalum, zirconium, strontium, lanthanum, neodymium, holmium,barium, lutetium, dysprosium, samarium, terbium, erbium, thulium,titanium, niobium, manganese, scandium, europium, tin, cerium, or anycombination thereof. The dopant can segregate to grain boundaries andmodify grain boundary diffusion rates to slow the rate of oxide scalegrowth.

In one or more embodiments, an aerospace component includes a coatingdisposed on a surface of a substrate. The surface or substrate includesor contains nickel, nickel superalloy, aluminum, chromium, iron,titanium, hafnium, alloys thereof, or any combination thereof. Thecoating has a thickness of less than 10 μm and contains an aluminumoxide layer. In some examples, the surface of the aerospace component isan interior surface within a cavity of the aerospace component. Thecavity can have an aspect ratio of about 5 to about 1,000 and thecoating can have a uniformity of less than 30% of the thickness acrossthe interior surface.

The crystalline protective coatings described above reduce the amount ofnickel containing oxides formed at the surface of the aerospacecomponent and further decreases the rate of aluminum depletion from theaerospace component. For example, utilizing the protective coatingsresults in less than 10% of nickel containing oxides from forming on thesurface of the aerospace component such as less than 5%. Moreover, theprotective coating having a crystalline assembly enhances the integrityand protective properties of the protective coating, as well asenhancing the strength, longevity, and durability of the protectivecoating. Utilizing the protective coating further reduces the oxidationrate of the surface of the aerospace component, increasing the oxidationand corrosion resistance of the aerospace component. By depositing theprotective coating using ALD or CVD, the protective coating issubstantially conformal.

While the foregoing is directed to examples of the present disclosure,other and further examples of the disclosure may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

What is claimed is:
 1. A method for depositing a coating on an aerospacecomponent, comprising: depositing a first deposited layer on a surfaceof an aerospace component by a chemical vapor deposition (CVD) process,the aerospace component comprising nickel and aluminum; converting thefirst deposited layer to a crystalline phase; and forming an aluminumoxide region between the first deposited layer and the aerospacecomponent, the aluminum oxide region having a crystalline assembly,wherein the first deposited layer and the aluminum oxide region form aprotective coating directly on the aerospace component, the protectivecoating formed conformally and following a surface topology of theaerospace component; and wherein the protective coating protects theaerospace component from corrosion and oxidation and decreases a rate ofdepletion of aluminum from the aerospace component.
 2. The method ofclaim 1, further comprising: depositing a second deposited layer on thefirst deposited layer by a second CVD process or an atomic layerdeposition (ALD) process prior to converting the first deposited layerto a crystalline phase, wherein the first deposited layer and the seconddeposited layer have different compositions from each other, and whereinconverting the first deposited layer to a crystalline phase furthercomprises forming a coalesced layer having the crystalline phase.
 3. Themethod of claim 2, wherein the first deposited layer comprises aluminumoxide and the second deposited layer comprises chromium oxide.
 4. Themethod of claim 2, further comprising: depositing one or more additionaldeposited layers on the second deposited layer prior to converting thefirst and second deposited layers to the crystalline phase; andconverting the first deposited layer, the second deposited layer, andthe one or more additional deposited layers to a coalesced layer havinga crystalline phase.
 5. The method of claim 4, further comprising anintermediate region imposed between the coalesced layer and theaerospace component, the intermediate region comprising an aluminumdepleted region of the aerospace component.
 6. The method of claim 1,wherein the first deposited layer comprises chromium oxide, and whereinforming the aluminum oxide region forms a coalesced layer comprisingchromium oxide, aluminum oxide, and a mixed chromium-aluminum oxide. 7.The method of claim 6, wherein the first deposited layer is deposited ata temperature of about 300 degrees Celsius to about 1100 degreesCelsius.
 8. The method of claim 1, wherein the aluminum oxide region isformed by annealing the first deposited layer at a temperature betweenabout 500 degrees Celsius to about 1100 degrees Celsius for a timeperiod of about 1 hour to about 15 hours.
 9. A method for depositing acoating on an aerospace component, comprising: depositing a firstdeposited layer on a surface of an aerospace component by a chemicalvapor deposition (CVD) process or an atomic layer deposition (ALD)process, the aerospace component comprising nickel and aluminum;performing a first annealing and oxidizing process to convert the firstdeposited layer into a preferred crystalline phase; depositing a seconddeposited layer by the CVD process or the ALD process on the firstdeposited layer; and performing a second annealing and oxidizing processto convert the second deposited layer into the preferred crystallinephase, wherein the first deposited layer and the second deposited layerform a protective coating directly on the aerospace component, theprotective coating formed conformally and following a surface topologyof the aerospace component; and wherein the protective coating protectsthe aerospace component from corrosion and oxidation and decreases arate of depletion of aluminum from the aerospace component.
 10. Themethod of claim 9, wherein the first deposited layer comprises chromiumoxide and the second deposited layer comprises aluminum oxide.
 11. Themethod of claim 9, an aluminum oxide region is formed between the firstdeposited layer and the aerospace component, the aluminum oxide regionhaving a crystalline assembly.
 12. The method of claim 9, wherein thefirst deposited layer comprising aluminum, wherein the second depositedlayer comprises chromium, and wherein the first annealing and oxidationprocess and the second annealing and oxidizing process are performed ata temperature between about 500 degrees Celsius to about 1200 degreesCelsius for a time period of about 1 hour to about 15 hours in air.